1. Field of the Invention
The present invention relates to a structure for mounting an electric component on a wiring board, which is suitable for various electronic circuit units and the like.
2. Description of the Related Art
FIG. 4 is a cross-sectional view showing essential parts of a structure for mounting an electronic component on a wiring board according to a related art. Next, the configuration of the structure for mounting an electronic component on a wiring board according to the related art will be described with reference to FIG. 4. An electronic component 51, such as a semiconductor chip or the like, has a main body portion 51a and a plurality of electrodes 51b provided on the bottom surface of the main body portion 51a. 
On a surface of a wiring board 52, wiring patterns 53 which are made of solderable metallic materials and have land portions 53a are provided. Further, a nonsolderable solder resist film 54 is provided on the entire surface of the wiring board 52 and on the wiring patterns 53 excluding the land portions 53a, such that soldering regions of the land portions 53a are formed by the solder resist film 54.
Electrodes 51b of the electronic component 51 are soldered to the land portions 53a by solders 55. Further, a gap provided between the main body portion 51a and the solder resist film 54 is filled with an adhesive (underfill resin) 56. Then, the main body portion 51a is adhered to the wiring board 52, such that the electronic component 51 is stably mounted. (For example, see Japanese Unexamined Patent Application Publication No. 8-88464)
However, in the structure for mounting an electronic component on a wiring board according to the related art, the solder resist film 54 is provided on the wiring patterns 53 excluding the land portions 53a and on the entire surface of the wiring board 52. Accordingly, it is difficult to form the solder resist film 54, which results in degrading productivity. Further, since the adhesive 56 is adhered to the solder resist film 54, the solder resist film 54 may be removed, such that the electronic component 51 may be mounted weakly.
As described above, in the structure for mounting an electronic component on a wiring board according to the related art, the solder resist film 54 is provided on the wiring patterns 53 excluding the land portions 53a and on the entire surface of the wiring board 52. Accordingly, it is difficult to form the solder resist film 54, which results in degrading productivity. Further, since the adhesive 56 is adhered to the solder resist film 54, the solder resist film 54 may be removed, such that the electronic component 51 may be mounted weakly.